1. Field of Invention
The present invention relates to fluid dispensers; particularly to fluid dispenser systems that use internal fluid containers having a collapsible, resilient, pump tube through which the fluid is dispensed; more particularly to dispenser systems having a pump tip at the end of the pump tube which restricts the flow of fluid between dispenses and regulates or directs the flow of fluid during dispenses, and most particularly to wall-mounted liquid soap dispensers using disposable soap containers known in the industry as "bag-in-a box" containers.
2. Description of Prior Art
The prior art of metered dispensing of single-use portions of fluids from dispensers using some sort of disposable, collapsible tube to which pressure is applied for flow control, is voluminous. The most significant benefit of this methodology is that the subject fluid never comes into direct contact with valves or pumps of conventional plumbing. Liquids and semi-liquids such as food materials, medicines, and cleaning materials are commonly dispensed from countless numbers of existing such dispensers in use around the world. New dispensers are being added to existing markets and new markets constantly.
Wall-mounted liquid soap dispensers which dispense small portions of detergent upon application of pressure to a dispensing arm or member are commonly found in business, industry and institutional restrooms, and constitute a significant specialty industry. The installed base of soap dispensers in the United States alone is estimated to exceed one million. Many of these still use a fixed reservoir which is refilled as required, but the industry trend is overwhelming in favor of dispensers that use sealed, disposable containers of soap having integral pump tubes and tips. The improvements in ease of service, maintenance and improved sanitation are compelling reasons to do so.
However, little of the published art focuses on the subject of the manual metering or pumping mechanism within the dispensers, particularly on the pump tip on the end of the pump tube operated in the most common dispensers. The pump tip performs several important functions; it has a nozzle to dispense the soap in the right direction, it opens on demand to dispense a metered portion of soap, and it closes off the flow of soap between dispenses.
The pump tips of the prior art are substantially supported within and by the pump tube, the lower end of the tube when installed being nested in a recess in the back plate of the dispenser. Some pump tips and nozzles are totally unsupported, otherwise, and are susceptible to movement in any direction, caused by movement of the pump tube. This can lead to misdirected dispenses, jams, and leaks.
Some pump tips have keyed surfaces that extend from below the lower edge of the pump tube to mate with corresponding surfaces in the lower end of the tube recess of compatible dispensers. The keyed surfaces act primarily to restrict the degree of cross-brand compatibility of soap containers to dispensers, but may contribute to some degree to prevent pump tubes and tips from being twisted or drawn up into the dispenser as the pump tube is manipulated by the pumping mechanism.
The "bag-in-a-box" containers hold the liquid soap or other desired material, in a collapsible, flexible bag within a cardboard or paperboard box which is closed for shipping and storage. The box is installed on a shelf in the dispenser, opened for use by tearing out a perforated section in the front and bottom of the box which leaves a slot through which the collapsible pump tube connected to the bottom of the bag is extracted and positioned in it's respective upper and lower tube locator recesses. The tube may be attached to the bag by a rotatable fitment which allows the tube and tip to be rotated as necessary to mate any keyed surfaces on the tip to the corresponding surfaces in the lower tube recess.
The pump tube is typically made of extruded or molded latex or similar material, and is typically two to four inches long, depending on the dispensers it is intended to fit. The pump tube is attached to or terminated by the pump tip and nozzle from which the fluid is dispensed.
Within the pump tip is a check valve that resists the free flow of fluid from the bag, but which will yield to the fluid pressure created by a manually-actuated pumping mechanism which squeezes the pump tube in a downward direction.
The pump lever actually pinches off the tube closer to the upper end, then squeezes the tube progressively downward to expel the trapped fluid through the pump tip. When the pressure on the tube is removed, the lower end check valve shuts, and the tube expands to its full size. It is the expansion of the pump tube after the dispense that draws more fluid from the bag into the tube, collapsing the bag by a proportionate volume.
The system is sized so that one or two strokes of the pump lever should dispense a sufficient volume of soap for the average user's immediate use.
The check valve may be incorporated into the lower end of the pump tube, rather than actually in the pump tip. Also, some designs include a second check valve on the upper end of the pump tube to prevent back flow of fluid into the bag during the pressure stroke on the pump tube.
In some systems the volume requirement necessitates a larger diameter pump tube than the dispenser's lower recess provides for. Some manufacturers use a molded-in necked-down lower end tube design to provide the desired working volume and still properly fit the tube recess. This necked-down feature creates a complex pump tube design that is inevitably more expensive to manufacture than simple, extruded pump hose that could be cut to length.
A dispenser cover opens to expose the interior of the dispenser for changing soap containers. The box of soap is placed on a supporting shelf in the upper part of the dispenser, and the pump tube is extended downward through a slot in the shelf and typically positioned into an upper pump tube recess and a lower pump tube recess with the working portion of the pump tube lying against a back plate or support wall of the dispenser.
The dispenser cover, when closed, positions a lever or pump arm or related pressure member in close proximity to the pump tube so that upon actuation, the pressure member squeezes the tube against the support wall in a downward direction, thus forcing a portion of the fluid in the tube through the pump tip and out the nozzle. The tube recovers it's shape when the lever is relaxed, allowing the tube's interior volume to be replenished with fluid from the bag.
It is important to reiterate that the known pump tube/tip designs universally extend the tubing into a lower tube recess as the primary means of providing lateral support to the pump tube during operation in the dispenser. Conversely, the lower tube locator recesses of known soap dispensers are universally designed with the outer diameter of the lower end of the intended pump tube as the size of the recess, clearly intending that the principle means of laterally securing the low end of the pump tube be by virtue of it's external contact with the walls of the recess, and thereby relegating the pump tip to the less rigid support provided by the interior walls of the pump tube.
This design standard has resulted in the problem of a lack of rigidity and structural integrity of the lower termination point of the pump hose, and the further problem that the pump tip and nozzle are not fully supported, secured or laterally restrained by dispenser structure, and may be twisted or misdirected by flexing of the pump tube in operations, or by external means such as user's hands or fingers, causing fluid to be dispensed in an unexpected direction, or possible malfunction or leakage of the dispenser.
Furthermore, in common dispensers there is no structural means provided for closing or fully securing the pump tip against forward movement within the lower pump tube recess, thus not excluding the possibility that a pump tip will become dislodged or misaligned during cover closure or operation, causing a malfunction, rupture, or related problem.
U.S. Pat. No. 5,265,772, Bartasevich, Nov. 30, 1993, discloses a typical dispenser system that uses a "bag-in-a-box" disposable container. The illustrations clearly show the reliance on a pump tip and tube combination whereby the outer diameter of the soft wall of the pump tube extends downward into the lower tube recess and provides the majority of contacting surface for lateral restraint of the tube in operation.
The pump tips and tubes of FIGS. 8A, 8B and 8C of this specification illustrate examples of the prior art of pump tip designs that presume pump tubes to extend into the lower recess of a common dispenser, the vertical height of the recess being the excess tube length illustrated in FIGS. 8A-8D by length L. FIGS. 1, 2 and 6 further illustrate a typical dispenser loaded with a fluid container with a pump tube and tip of the prior art wherein the tube extends into the lower tube recess and provides only a soft contact surface for lateral support.
In summary, the box, bag, pump tube and pump tip portion of typical dispensing systems, in the present practice and direction the industry is heading, are disposable and consequently very price sensitive. Therefore subtle improvements that will lower unit costs of the disposable package by small fractions of a cent, when multiplied by the total market, become very important. Also, the large installed base of dispensers means that improvements to the disposable portion of the hardware that will work with the existing installed dispensers will reach and benefit more users far faster than improvements to the dispenser. Finally, the present scheme of pump tubes and tips is not the product of a clean design, but simply the present state of an evolving industry. The pump tubes and tips of the prior art, supported mainly by the exterior walls of the excess length of the soft latex pump tube wall have been known to become disengaged, to rupture, and to misdirect the dispensed materials. Also, as always, the cost of disposable hardware is an issue.